diff options
Diffstat (limited to 'compiler/rustc_const_eval/src/util')
| -rw-r--r-- | compiler/rustc_const_eval/src/util/aggregate.rs | 77 | ||||
| -rw-r--r-- | compiler/rustc_const_eval/src/util/alignment.rs | 63 | ||||
| -rw-r--r-- | compiler/rustc_const_eval/src/util/call_kind.rs | 146 | ||||
| -rw-r--r-- | compiler/rustc_const_eval/src/util/collect_writes.rs | 36 | ||||
| -rw-r--r-- | compiler/rustc_const_eval/src/util/find_self_call.rs | 36 | ||||
| -rw-r--r-- | compiler/rustc_const_eval/src/util/mod.rs | 10 |
6 files changed, 368 insertions, 0 deletions
diff --git a/compiler/rustc_const_eval/src/util/aggregate.rs b/compiler/rustc_const_eval/src/util/aggregate.rs new file mode 100644 index 000000000..180a40043 --- /dev/null +++ b/compiler/rustc_const_eval/src/util/aggregate.rs @@ -0,0 +1,77 @@ +use rustc_index::vec::Idx; +use rustc_middle::mir::*; +use rustc_middle::ty::{Ty, TyCtxt}; +use rustc_target::abi::VariantIdx; + +use std::convert::TryFrom; +use std::iter::TrustedLen; + +/// Expand `lhs = Rvalue::Aggregate(kind, operands)` into assignments to the fields. +/// +/// Produces something like +/// +/// (lhs as Variant).field0 = arg0; // We only have a downcast if this is an enum +/// (lhs as Variant).field1 = arg1; +/// discriminant(lhs) = variant_index; // If lhs is an enum or generator. +pub fn expand_aggregate<'tcx>( + orig_lhs: Place<'tcx>, + operands: impl Iterator<Item = (Operand<'tcx>, Ty<'tcx>)> + TrustedLen, + kind: AggregateKind<'tcx>, + source_info: SourceInfo, + tcx: TyCtxt<'tcx>, +) -> impl Iterator<Item = Statement<'tcx>> + TrustedLen { + let mut lhs = orig_lhs; + let mut set_discriminant = None; + let active_field_index = match kind { + AggregateKind::Adt(adt_did, variant_index, _, _, active_field_index) => { + let adt_def = tcx.adt_def(adt_did); + if adt_def.is_enum() { + set_discriminant = Some(Statement { + kind: StatementKind::SetDiscriminant { + place: Box::new(orig_lhs), + variant_index, + }, + source_info, + }); + lhs = tcx.mk_place_downcast(orig_lhs, adt_def, variant_index); + } + active_field_index + } + AggregateKind::Generator(..) => { + // Right now we only support initializing generators to + // variant 0 (Unresumed). + let variant_index = VariantIdx::new(0); + set_discriminant = Some(Statement { + kind: StatementKind::SetDiscriminant { place: Box::new(orig_lhs), variant_index }, + source_info, + }); + + // Operands are upvars stored on the base place, so no + // downcast is necessary. + + None + } + _ => None, + }; + + let operands = operands.enumerate().map(move |(i, (op, ty))| { + let lhs_field = if let AggregateKind::Array(_) = kind { + let offset = u64::try_from(i).unwrap(); + tcx.mk_place_elem( + lhs, + ProjectionElem::ConstantIndex { offset, min_length: offset + 1, from_end: false }, + ) + } else { + let field = Field::new(active_field_index.unwrap_or(i)); + tcx.mk_place_field(lhs, field, ty) + }; + Statement { + source_info, + kind: StatementKind::Assign(Box::new((lhs_field, Rvalue::Use(op)))), + } + }); + [Statement { source_info, kind: StatementKind::Deinit(Box::new(orig_lhs)) }] + .into_iter() + .chain(operands) + .chain(set_discriminant) +} diff --git a/compiler/rustc_const_eval/src/util/alignment.rs b/compiler/rustc_const_eval/src/util/alignment.rs new file mode 100644 index 000000000..4f39dad20 --- /dev/null +++ b/compiler/rustc_const_eval/src/util/alignment.rs @@ -0,0 +1,63 @@ +use rustc_middle::mir::*; +use rustc_middle::ty::{self, TyCtxt}; +use rustc_target::abi::Align; + +/// Returns `true` if this place is allowed to be less aligned +/// than its containing struct (because it is within a packed +/// struct). +pub fn is_disaligned<'tcx, L>( + tcx: TyCtxt<'tcx>, + local_decls: &L, + param_env: ty::ParamEnv<'tcx>, + place: Place<'tcx>, +) -> bool +where + L: HasLocalDecls<'tcx>, +{ + debug!("is_disaligned({:?})", place); + let Some(pack) = is_within_packed(tcx, local_decls, place) else { + debug!("is_disaligned({:?}) - not within packed", place); + return false; + }; + + let ty = place.ty(local_decls, tcx).ty; + match tcx.layout_of(param_env.and(ty)) { + Ok(layout) if layout.align.abi <= pack => { + // If the packed alignment is greater or equal to the field alignment, the type won't be + // further disaligned. + debug!( + "is_disaligned({:?}) - align = {}, packed = {}; not disaligned", + place, + layout.align.abi.bytes(), + pack.bytes() + ); + false + } + _ => { + debug!("is_disaligned({:?}) - true", place); + true + } + } +} + +fn is_within_packed<'tcx, L>( + tcx: TyCtxt<'tcx>, + local_decls: &L, + place: Place<'tcx>, +) -> Option<Align> +where + L: HasLocalDecls<'tcx>, +{ + place + .iter_projections() + .rev() + // Stop at `Deref`; standard ABI alignment applies there. + .take_while(|(_base, elem)| !matches!(elem, ProjectionElem::Deref)) + // Consider the packed alignments at play here... + .filter_map(|(base, _elem)| { + base.ty(local_decls, tcx).ty.ty_adt_def().and_then(|adt| adt.repr().pack) + }) + // ... and compute their minimum. + // The overall smallest alignment is what matters. + .min() +} diff --git a/compiler/rustc_const_eval/src/util/call_kind.rs b/compiler/rustc_const_eval/src/util/call_kind.rs new file mode 100644 index 000000000..af9d83f06 --- /dev/null +++ b/compiler/rustc_const_eval/src/util/call_kind.rs @@ -0,0 +1,146 @@ +//! Common logic for borrowck use-after-move errors when moved into a `fn(self)`, +//! as well as errors when attempting to call a non-const function in a const +//! context. + +use rustc_hir::def_id::DefId; +use rustc_hir::lang_items::LangItemGroup; +use rustc_middle::ty::subst::SubstsRef; +use rustc_middle::ty::{self, AssocItemContainer, DefIdTree, Instance, ParamEnv, Ty, TyCtxt}; +use rustc_span::symbol::Ident; +use rustc_span::{sym, DesugaringKind, Span}; + +#[derive(Clone, Copy, PartialEq, Eq, Debug)] +pub enum CallDesugaringKind { + /// for _ in x {} calls x.into_iter() + ForLoopIntoIter, + /// x? calls x.branch() + QuestionBranch, + /// x? calls type_of(x)::from_residual() + QuestionFromResidual, + /// try { ..; x } calls type_of(x)::from_output(x) + TryBlockFromOutput, +} + +impl CallDesugaringKind { + pub fn trait_def_id(self, tcx: TyCtxt<'_>) -> DefId { + match self { + Self::ForLoopIntoIter => tcx.get_diagnostic_item(sym::IntoIterator).unwrap(), + Self::QuestionBranch | Self::TryBlockFromOutput => { + tcx.lang_items().try_trait().unwrap() + } + Self::QuestionFromResidual => tcx.get_diagnostic_item(sym::FromResidual).unwrap(), + } + } +} + +#[derive(Clone, Copy, PartialEq, Eq, Debug)] +pub enum CallKind<'tcx> { + /// A normal method call of the form `receiver.foo(a, b, c)` + Normal { + self_arg: Option<Ident>, + desugaring: Option<(CallDesugaringKind, Ty<'tcx>)>, + /// Whether the self type of the method call has an `.as_ref()` method. + /// Used for better diagnostics. + is_option_or_result: bool, + }, + /// A call to `Fn(..)::call(..)`, desugared from `my_closure(a, b, c)` + FnCall { fn_trait_id: DefId, self_ty: Ty<'tcx> }, + /// A call to an operator trait, desugared from operator syntax (e.g. `a << b`) + Operator { self_arg: Option<Ident>, trait_id: DefId, self_ty: Ty<'tcx> }, + DerefCoercion { + /// The `Span` of the `Target` associated type + /// in the `Deref` impl we are using. + deref_target: Span, + /// The type `T::Deref` we are dereferencing to + deref_target_ty: Ty<'tcx>, + self_ty: Ty<'tcx>, + }, +} + +pub fn call_kind<'tcx>( + tcx: TyCtxt<'tcx>, + param_env: ParamEnv<'tcx>, + method_did: DefId, + method_substs: SubstsRef<'tcx>, + fn_call_span: Span, + from_hir_call: bool, + self_arg: Option<Ident>, +) -> CallKind<'tcx> { + let parent = tcx.opt_associated_item(method_did).and_then(|assoc| { + let container_id = assoc.container_id(tcx); + match assoc.container { + AssocItemContainer::ImplContainer => tcx.trait_id_of_impl(container_id), + AssocItemContainer::TraitContainer => Some(container_id), + } + }); + + let fn_call = parent + .and_then(|p| tcx.lang_items().group(LangItemGroup::Fn).iter().find(|did| **did == p)); + + let operator = (!from_hir_call) + .then(|| parent) + .flatten() + .and_then(|p| tcx.lang_items().group(LangItemGroup::Op).iter().find(|did| **did == p)); + + let is_deref = !from_hir_call && tcx.is_diagnostic_item(sym::deref_method, method_did); + + // Check for a 'special' use of 'self' - + // an FnOnce call, an operator (e.g. `<<`), or a + // deref coercion. + let kind = if let Some(&trait_id) = fn_call { + Some(CallKind::FnCall { fn_trait_id: trait_id, self_ty: method_substs.type_at(0) }) + } else if let Some(&trait_id) = operator { + Some(CallKind::Operator { self_arg, trait_id, self_ty: method_substs.type_at(0) }) + } else if is_deref { + let deref_target = tcx.get_diagnostic_item(sym::deref_target).and_then(|deref_target| { + Instance::resolve(tcx, param_env, deref_target, method_substs).transpose() + }); + if let Some(Ok(instance)) = deref_target { + let deref_target_ty = instance.ty(tcx, param_env); + Some(CallKind::DerefCoercion { + deref_target: tcx.def_span(instance.def_id()), + deref_target_ty, + self_ty: method_substs.type_at(0), + }) + } else { + None + } + } else { + None + }; + + kind.unwrap_or_else(|| { + // This isn't a 'special' use of `self` + debug!(?method_did, ?fn_call_span); + let desugaring = if Some(method_did) == tcx.lang_items().into_iter_fn() + && fn_call_span.desugaring_kind() == Some(DesugaringKind::ForLoop) + { + Some((CallDesugaringKind::ForLoopIntoIter, method_substs.type_at(0))) + } else if fn_call_span.desugaring_kind() == Some(DesugaringKind::QuestionMark) { + if Some(method_did) == tcx.lang_items().branch_fn() { + Some((CallDesugaringKind::QuestionBranch, method_substs.type_at(0))) + } else if Some(method_did) == tcx.lang_items().from_residual_fn() { + Some((CallDesugaringKind::QuestionFromResidual, method_substs.type_at(0))) + } else { + None + } + } else if Some(method_did) == tcx.lang_items().from_output_fn() + && fn_call_span.desugaring_kind() == Some(DesugaringKind::TryBlock) + { + Some((CallDesugaringKind::TryBlockFromOutput, method_substs.type_at(0))) + } else { + None + }; + let parent_did = tcx.parent(method_did); + let parent_self_ty = (tcx.def_kind(parent_did) == rustc_hir::def::DefKind::Impl) + .then_some(parent_did) + .and_then(|did| match tcx.type_of(did).kind() { + ty::Adt(def, ..) => Some(def.did()), + _ => None, + }); + let is_option_or_result = parent_self_ty.map_or(false, |def_id| { + matches!(tcx.get_diagnostic_name(def_id), Some(sym::Option | sym::Result)) + }); + CallKind::Normal { self_arg, desugaring, is_option_or_result } + }) +} diff --git a/compiler/rustc_const_eval/src/util/collect_writes.rs b/compiler/rustc_const_eval/src/util/collect_writes.rs new file mode 100644 index 000000000..8d92bb359 --- /dev/null +++ b/compiler/rustc_const_eval/src/util/collect_writes.rs @@ -0,0 +1,36 @@ +use rustc_middle::mir::visit::PlaceContext; +use rustc_middle::mir::visit::Visitor; +use rustc_middle::mir::{Body, Local, Location}; + +pub trait FindAssignments { + // Finds all statements that assign directly to local (i.e., X = ...) + // and returns their locations. + fn find_assignments(&self, local: Local) -> Vec<Location>; +} + +impl<'tcx> FindAssignments for Body<'tcx> { + fn find_assignments(&self, local: Local) -> Vec<Location> { + let mut visitor = FindLocalAssignmentVisitor { needle: local, locations: vec![] }; + visitor.visit_body(self); + visitor.locations + } +} + +// The Visitor walks the MIR to return the assignment statements corresponding +// to a Local. +struct FindLocalAssignmentVisitor { + needle: Local, + locations: Vec<Location>, +} + +impl<'tcx> Visitor<'tcx> for FindLocalAssignmentVisitor { + fn visit_local(&mut self, local: Local, place_context: PlaceContext, location: Location) { + if self.needle != local { + return; + } + + if place_context.is_place_assignment() { + self.locations.push(location); + } + } +} diff --git a/compiler/rustc_const_eval/src/util/find_self_call.rs b/compiler/rustc_const_eval/src/util/find_self_call.rs new file mode 100644 index 000000000..33ad128ee --- /dev/null +++ b/compiler/rustc_const_eval/src/util/find_self_call.rs @@ -0,0 +1,36 @@ +use rustc_middle::mir::*; +use rustc_middle::ty::subst::SubstsRef; +use rustc_middle::ty::{self, TyCtxt}; +use rustc_span::def_id::DefId; + +/// Checks if the specified `local` is used as the `self` parameter of a method call +/// in the provided `BasicBlock`. If it is, then the `DefId` of the called method is +/// returned. +pub fn find_self_call<'tcx>( + tcx: TyCtxt<'tcx>, + body: &Body<'tcx>, + local: Local, + block: BasicBlock, +) -> Option<(DefId, SubstsRef<'tcx>)> { + debug!("find_self_call(local={:?}): terminator={:?}", local, &body[block].terminator); + if let Some(Terminator { kind: TerminatorKind::Call { func, args, .. }, .. }) = + &body[block].terminator + { + debug!("find_self_call: func={:?}", func); + if let Operand::Constant(box Constant { literal, .. }) = func { + if let ty::FnDef(def_id, substs) = *literal.ty().kind() { + if let Some(ty::AssocItem { fn_has_self_parameter: true, .. }) = + tcx.opt_associated_item(def_id) + { + debug!("find_self_call: args={:?}", args); + if let [Operand::Move(self_place) | Operand::Copy(self_place), ..] = **args { + if self_place.as_local() == Some(local) { + return Some((def_id, substs)); + } + } + } + } + } + } + None +} diff --git a/compiler/rustc_const_eval/src/util/mod.rs b/compiler/rustc_const_eval/src/util/mod.rs new file mode 100644 index 000000000..a1876bed8 --- /dev/null +++ b/compiler/rustc_const_eval/src/util/mod.rs @@ -0,0 +1,10 @@ +pub mod aggregate; +mod alignment; +mod call_kind; +pub mod collect_writes; +mod find_self_call; + +pub use self::aggregate::expand_aggregate; +pub use self::alignment::is_disaligned; +pub use self::call_kind::{call_kind, CallDesugaringKind, CallKind}; +pub use self::find_self_call::find_self_call; |